Hyaluronic acid capsule and the role of streptococcal entry into keratinocytes in invasive skin infection

J Clin Invest. 1996 Nov 1;98(9):1954-8. doi: 10.1172/JCI118998.


It has been suggested that entry of pathogenic bacteria, including streptococci, into epithelial cells may represent an early stage of invasive infections. We found that poorly encapsulated wild-type strains and unencapsulated mutants of group A Streptococcus entered cultured human keratinocytes with high efficiency, while strains that produced large amounts of hyaluronic acid capsule did not, regardless of M-protein type or clinical source of the isolate. However, encapsulated streptococci produced extensive local necrosis and systemic infection in a mouse model of skin infection, while an isogenic acapsular strain did not. The results implicate the hyaluronic acid capsule as a virulence factor in soft tissue infection. Entry of poorly encapsulated group A Streptococcus into human epithelial cells does not appear to represent an initial step in invasive disease; rather, the capacity of encapsulated strains to avoid uptake by epithelial cells is associated with enhanced virulence in skin and soft tissue infection.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Bacterial Capsules / physiology*
  • Humans
  • Hyaluronic Acid / physiology*
  • Keratinocytes / microbiology*
  • Mice
  • Skin Diseases / microbiology*
  • Streptococcus pyogenes / pathogenicity*
  • Tumor Cells, Cultured


  • Hyaluronic Acid